Venid: If you're familiar with only Latin American Spanish, you might not know this verb form well. The -id is the the ending for a command that goes with vosotros, so venid means "you (plural) come" or simply "come."
Canto: Although this word, meaning "song" or "the act of singing," isn't particularly common, you should be able to guess its meaning if you know that the verb cantar means "to sing."
Pueblito: This is a diminutive form of pueblo, meaning (in this context) "town" or "village." You may have noticed that in the translation of "O Little Town of Bethlehem" that the form pueblecito is used. There is no difference in meaning. Diminutive endings can sometimes be applied freely; in this case pueblito was used because it fit the rhythm of the song.
Belén: This is the Spanish name for Bethlehem. It isn't unusual for names of cities, particularly those well-known centuries ago, to have different names in different languages. Interestingly, in Spanish the word belén (not capitalized) has come to refer to a nativity scene or a crib. It also has a colloquial use referring to confusion or a confusing problem.
Cantadle: This is the familiar command form of cantar (cantad) and le is a pronoun meaning "him." "Cantadle loores, coros celestiales" means "sing him praises, heavenly choirs."
Resuene: This is a conjugated form of the verb resonar, "to resound" or "to echo." Thus "resuene el eco angelical" means "may the angelical echo resound."
Loor: This is an uncommon word meaning "praise." It is seldom used in everyday speech, having mostly liturgical use.
Señor: In everyday use, señor is used as a man's courtesy title, the same as "Mr." Unlike the English word "Mr.," the Spanish señor can also mean "lord." In Christianity, it becomes a way of referring to the Lord Jesus.
Nos gozamos: This is an example of a reflexive verb usage. By itself, the verb gozar would typically mean "to have joy" or something similar. In the reflexive form, gozarse typically would be translated as "rejoice."
Carne: In everyday use, this word typically means "meat." Here it means "flesh," the sentence being a loose translation of "now in flesh appearing."
Verbo del Padre: As you might guess, the most common meaning of verbo is "verb." Here, verbo is an allusion to the Gospel of John, where Jesus is referred to as "the Word" (logos in the original Greek). The traditional Spanish translation of the Bible, the Reina-Valera, uses the word Verbo in translating the first verse of John from Greek.
